The subject matter disclosed herein relates generally to power systems and, more particularly, to techniques for regulating power quality.
As consumers and industries continue to increasing rely upon electrical power systems to supply power to variety of loads, which may include various types of electronic devices ranging from consumer household electronics to industrial equipment, issues regarding power quality is also becoming an increasing concern. For example, events that affect power quality (e.g., which may manifest as faults or variations in a transmitted power signal) may include voltage sags, swells, harmonics, surges, or unbalancing, all of which may negatively affect power usage and may also cause damage to loads coupled to a power system, particularly electrically sensitive loads.
With regard to voltage sag conditions, voltage sags are typically understood to be a sudden reduction in RMS voltage, sometimes for a duration from approximately half a cycle to one minute. A number of causes may contribute to voltage sags that occur in a power transmission system, such as tripped circuit breakers, short circuit faults, electrical equipment failure (e.g., cable faults, overloading, etc.), inclement weather, and/or pollution. Additionally, voltage sags may also occur due to events at the receiving end of a power signal, such as electrical faults within an industrial facility or the startup of large induction-based devices, such as an induction motor. Unfortunately, voltage sags may contribute to the interruption and/or malfunction of voltage sensitive loads, which may include adjustable-speed drives, generators, motors (e.g., synchronous, induction, etc.) and sensitive control equipment (e.g., computers, programmable logic controllers, etc.). Further, recent studies have shown that voltage sag conditions have a generally high probability of occurring, and are one of the most frequently occurring types of power quality events. Accordingly, there exists a need to better control and regulate power quality via the detection and correction of voltage sag conditions to better protect voltage sensitive loads from interruption and/or malfunction.